System and method for washing articles employing a densified cleaning solution, and use of a fluid displacement device therein

A dry cleaning system arranged for washing articles employing a cleaning solution, said cleaning solution comprising a liquid and a vapor, said system comprising:

• a wash tank for washing an article to be washed with said cleaning solution at hyperatmospheric pressure;
• a central storage tank for storing said cleaning solution, wherein said central storage tank is closeably connected to said wash tank;
• a cleaning device connected to the wash tank for cleaning the cleaning solution;
• and
• a single fluid displacement device being a pumping and compressing unit connected through a wash tank-pump line to said wash tank for transfer of cleaning solution from the wash tank to the fluid displacement device and through a further line for transfer of liquid from the fluid displacement device to the wash tank wherein the wash-tank line and the further line are each closeable by a respective valve and said single fluid displacement device being arranged for:
• transferring said cleaning solution in liquid form through said dry cleaning system in a first operational mode of a wash cycle;
• continuously cleaning the cleaning solution in liquid form by transferring the cleaning solution in liquid form through the cleaning device during the first operational mode of the wash cycle;
• and
• reducing the pressure in said wash tank toward atmospheric pressure in a second operational mode of the wash cycle, after removal of the liquid cleaning solution from the wash tank to the central storage tank, by removing the vapor from the wash tank by means of compressing the removed vapor,
• wherein the fluid displacement device is a positive-displacement device, being a reciprocating pump/compressor device or a piston device to pressurize fluid, arranged for transferring liquid and vapor fluid, and for compressing vapor fluid.